Centrifugal switch



May 6, 1952 Filed Oct. 27 1949 (o o qlp Q0 w. z. wEsT, JR., E-rAl.2,595,621

CENTRIFUGAL SWITCH I5 Sheets-Sheer. l

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. INVENTORS Villl's Z. WGSJ.

May 6, 1952 -w. z. WEST, JR., -Er A1. 2,595,621

CENTRIFUGAL SWITCH Filed Oct. 27, 1949 5 Sheets-Sheet 2 @Mxwm May 6 1952w. z. wEsT, JR., ET/AL 2,595,621

CENTRIFUGAL SWITCH 5 Sheets-Sheet 3 Filed Oct. 2'?, 1949 .16; @QL/)14MPatented May 6, 195.2

CENTRIFUGAL SW-ITCH Willis Z. West, Jr., and Morgan F. Gamble,Winston-Salem, N. C.

Appiication October 27, 1949, Serial No. 123,880

Claims. (Cl. 20D-81)) Our invention relates to a switch of the typeactuated by centrifugal force to open or close a circuit.

A primary object of our invention is to provide a switch of thecharacter mentioned, to ce mounted upon an armature shaft of a motor,and having means for electrically connecting terminals of the switchwhen the armature shaft is at rest, or vrotating slowly, and todisconnect the terminals when the rotational speed of the armature shaftincreases.

A further object is to provide a centrifugal force actuated switch whichemploys a toggle spring to govern the movement of a conducting elementwithin the switch when the switch rotates, so that the element will opena starting circuit at approximately 80 percent of full motor speed, andclose the circuit when the motor is slowing down, at a lower motorspeed, which is desirable.

A further object is to provide a switch of the above mentioned typewhich is axially thin and radially wide, so as to be very compact andoccupy a minimum axial space upon the armature shaft.

A further object is to provide a switch of the class mentioned having anovel and simplified arrangement of exposed brushes which operate atopposite sides of the switch.

A further object is tov provide a centrifugal force actuated switchwhich has exceptionally large contact areas for brushes, and largeswitch contacts.

A further object is to provide novel means for sealing the switchcontacts from dust and dirt, to eliminate noise, and to guide thebrushes so that their wear will be reduced to a minimum.

A still further object of our invention is to provide a switch of theabove mentioned character which is extremely strong and durable so thatit will have an exceptionally long life.

Other objects and advantages of the invention will he'apparent duringthe course of the following description.

In the accompanying drawings, forming a part of this application, and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a perspective view of a switch embodying our invention,

Figure 2 is a side elevation of the same,

Figure 3 is a plan view of the switch as shown in Figure 2,

Figure 4 is a vertical section taken on line 4--4 of Figure 3, parts inelevation, and parts omitted,

Figure 5 is an enlarged fragmentary vertical section taken on line5-5 ofFigure 4,

Figure 6 is an exploded perspective view of the switch,

Figure '7 is a horizontal section taken on line 'I-1 of Figure 2,

Figure 8 is a vertical section taken on line 8 8 of Figure 2,

FigureV 9 is a fragmentary radial section taken on line 9-9 of Figure 2,

Figure 10 is a similar section taken on line Ill--IU of Figure 2,

Figure 11 is a fragmentary vertical section taken on line I I--I I ofFigure 2,

Figure 12 is a planned view of the switch device, parts being taken insection substantially on the line I2-*I2 of Figure 4,

Figure 13 is a vertical section taken on line I3-I3 of Figure 2,

Figure 14 is a side elevation of the switch, showing a modified form ofholder for the plate brushes,

Figure 15 is an exploded perspective View of the plate brushes holder,

Figure 16 is a planned View of the complete devlce,

Figure 17 is a longitudinal section taken on line I'I-I 'I of Figure 14,and,

Figure 18 is an enlarged horizontal section taken o-n line I8-I8 ofFigure 14.

In the drawings, where for the purpose of illustration is shown apreferred example of our invention, the numeral I5 designates a disc orcarrier, formed of electric insulating material, which disc iscylindrical, axially thin, and radially wide, as shown. The disc orcarrier I5 includes a central cylindrical hub portion I6, extendingaxially outwardly of the disc I5 upon both sides of the same, andforming axially oppositely disposed annular shoulders I'I, which co-actwith opposed flat radially wide annular faces I8 of the disc I5, in amanner to be described. The hub portion I5 has a central axial bore I9for receiving the armature shaft S of an electric motor. The bore I9 isof such diameter that the switch may be pressed onto the armature shaftof the particular size for which the switch is designed. The hub ISprojects axially equidistantly upon opposite sides of the disc I5, andis preferably integral with the disc. The outside diameter of the hub I6is substantially less than the outside diameter of the disc I5, asshown, and the combined axial length of the disc and hub is relativelyshort. The disc I5 is provided outwardly of the hub I6 with an arcuateopening or slot 2D, which preferably extends circumferentially fornearly 9) degrees, and which has an inner` arcuate side 2 l, arrangednear and slightly radially outwardly of the periphery oi the hub E5. Anouter arcuate side 22 of the slot 2li is arranged near and inwardly ofthe periphery of the disc I5, so that the slot 223 occupies nearly theentire radial width of the disc outwardly of the periphery of the hub,Figure 4. Arcuate sides 2| and 22 of the slot 20 are preierablyconcentric with the hub I and bore i9. The right and left ends 23 and 24of the slot 25 are circularly curved. A shallow axial groove 25 isformed in the inner side 2i within the longitudinal center of the slot20, Figures 2, 1i, 5, 6, 9. The groove 2G extends through one end of thehub portion I5 and terminates short ci the other end of the hub portionl5.

Removably mounted within the arcuate slot 25 is an arcuate conductingelement ci segment 2l of brass, bronze or the like. rllhis conductingsegment 27 has a radial thickness substantially less than the radialwidth of the slot 2l] and the segment is substantially shorter than theslot, Figure 5. The inner and outer arcuate sides 23 and 29 of theconducting segment are preferably substantially concentric with thesides oi the slot 25. The left end of the conducting segment 21, Figure4, adjacent to the end 24, is rounded and is provided with a transverseopening 3l for receiving a metal pin 32, secured to a slip ring to bedescribed. The opposite end SI of the conducting segment 2l' is providedwith a notch 34, detachably holding one end of a generally U-shapedtoggle spring 35 of suitable metal. The toggle spring has an inner side35', and the closed end 35 of the toggle spring 35 is arranged near theend 23 of the slot. The outer side 3'5 of the toggle spring is arrangednear and spaced from the outer side 22 of the slot. The free end of theside 3l is bent radially outwardly to form a short radial extension 55,engaging in a notch 39 formed in the outer side 22 and extending throughthe axial length of the disc I5. Y

Arranged diametrically opposite the conducting segment 27 and formed inthe disc I5, is an arcuate slot 40, extending through both ends of thedisc I5. The slot 40 receives an arcuate counter weight 4I rigidlysecured therein. The counterweight has substantially the same weight asthe conducting segment 2l and serves to balance the switch duringrotation. Removably mounted upon the opposite sides of the disc orcarrier l5 are flat annular brush plates or slip rings 42 and 43, whichare axially thin and radially wide. The brush plates 42 and 43 have thesame radial width as the faces I3 of the disc, and are provided adjacentto their peripheries with axially extending annular flanges 44. Thebrush plates or slip rings are also provided with axially extendingannular inner flanges 45. The flanges 44 and 45 extend axially for equaldistances, and are substantially flush with the opposite ends oi the hubportion I5, Figure '7. The annular flanges 44 have their peripheriesflush with the periphery of the disc I5, and the inner annular flange 45engage over the periphery of the hub portion I6 upon opposite sides oithe disc I5 and have a snug nt therewith so that they will not turntherein, yet may be removed by a suitable tool. A thin flat annularinsulating washer 46 is arranged between the brush plate or slip ring 43and the adjacent face of the disc I5, covers the adjacent sides of theslots 2U and 40, and maintains the brush plate or slip ring 43 insulatedfrom the conducting segment 2I and counterweight 4I.

' or trunnion 55.

The metal pin 32 is carried by the slip ring 42, and pivotly supportsthe conducting segment 21 and also electrically connects it with theslip ring 42. A metallic conducting pin 4l is rigidly secured to theslip ring 42 and extends through an axial opening 4l formed in the discI5 and this opening leads into a groove 48 formed in one face I3 of thedisc l5. The free end of the conducting pin 4l is slotted to receive awire 45 which is secured within the slotted end by solder or the like.The Wire is permanently electrically connected with the conductingsegment 2l. It is thus seen that the conducting segment is in permanentelectrical connection with the slip ring 42. The slip ring 43 carries ashort hat metallic conducting tab 48 rigidly secured to the inner faceof the inner i'lange 45, as by welding, and the tab 46 projects axiallyinwardly beyond the slip ring 43 and is held within the groove 25. Thisgroove 25 terminates short oi the slip ring 42 so that the tab isinsulated from the slip ring 42. The conducting tab 48 has a contactpoint 49 secured to its outer side, and this contact point is arrangedto engage and disengage a contact point secured to the inner side 28 ofthe arcuate conducting segment 27. It is thus seen that the contactpoints 45 and 5S serve to electrically connect and disconnect conductingsegment 21 with and from the slip ring 43, while the conducting segment2 is in permanent electrical connection with the slip ring 42. Attentionis called to the fact that when the parts are assembled as shown inFigure 2, the slip rings 42 and 45 seal the slot 25 against dirt orother foreign matter and the conducting tab 48 also closes the groove26. The inner flanges 45 snugly engages over the periphery of the hub.portion I6. It is thus seen that the slot 25 is held dirt or dustproof, to a high degree, thus protecting the contact points 49 and 5G,and associated elements arranged within the groove 25.

Freely slidably mounted between the inner and outer annular flanges 45and 44 upon the metal brush plates 42 and 43, are flat thin platebrushes formed of carbon or the like. These plate brushes arecircumferentially elongated and arcuate, as shown, and have their innerflat faces slidably contacting the outer faces of the brush plates 42and 43. The plate brushes 5I are radially wide and extend between theannular anges 44 and 45 and their inner and outer arcuate sides 52 and53 slidably contact the flanges 44 and 45 to be guided thereby. Theplate brushes 5I are slightly thicker axially than the axial Widths ofthe flanges 44 and 45, so that the plate brushes project axially beyondthe ends of the hub portions I5, Figure 7. The flanges 44 and 45, inaddition to guiding the plate brushes. serve to make their operationvery quiet.

Means are provided to hold the plate brushes `5I against rotation withthe carrier or disc I5. These means include a ilat thin plate 54arranged upon one side of the switch and having a radially inwardlyextending arm 55, having rigidly secured thereto an axially inwardlyextending pin The arm 55 lies adjacent to the outer side of one platebrush 5I, and the pin 55 engages within an opening 57 formed in theouter side of each plate brush, at the longitudinal center of the same.The plate 54 further includes a rectangular main body portion 58,integral with the extension 55 and arranged near the periphery of thedisc I5 and spaced therefrom, Figure 7. The body portion 58 is providedin one end with a relatively large opening 59, and in its opposite endwith a small opening 55, for the 5. purposes to be described. .Agenerally Z-shaped plate 6I is provided opposite the ,plate 54. TheZ-shaped plate includes a radially inwardly extending arm 62, arrangedopposite the arm 55 and adjacent to the outer face of the other platebrush I. The arm 62 carries an axially inwardly extending pin ortrunnion 63, identical with the trunnion 56 for engagement in theopening 51 of the adjacent plate brush 5I. The Z-shaped plate 6I furtherincludes an axially extending portion 64 which extends near and spacedfrom the periphery of the disc I5, Figure 7; and secured to the innerend of the portion 64 is a main body portion B5, which is rectangularand arranged opposite the rectangular main body portion 58 and spacedtherefrom. The main body portion 95 is provided in one end with arelatively large opening 56, having the same diameter as the opening 59,and in its opposite end with a small opening 61, having the samediameter as the opening 66.` The opening G6 is arranged in axialalignment with the opening 60, while the opening 61 is in axialalignment with the opening 59.

A non-conducting fiber strip or bar 68 having a plurality oflongitudinally spaced adjusting openings 69 is arranged between the bodyportions 58 and 95 of the plates 54 and 6I, as shown. rihe openings 69are of the-same diameter as the openings 59 and 66. Tubular insulatingbushings 15 are inserted from opposite sides of the bar 63, through thelarge openings 59 and 66, of the plates 54 and 6I, Figure 13. Thebushings 10 are of such length that when their heads 1l engage the outerfaces of they plates 54 and 6I, their inner ends are flush with theopposite sides of the bar 68, Figure 13. Tubular conducting rivets 12,of copper, brass, or the like, are to be inserted through the bushings10 from their ends having the heads 1I. These tubular conducting rivetsextend entirely through the insulating bushings and through the openings6I) and 61 of the platesI 54 and 6I, which are upon opposite sides ofthe bar 68. The ends of the rivets 12 which extend through the openings60 and 61 are peened over as shown at 13, for rigidly securing the partstogether in assembly. The rivets 12 have heads 14 spaced from the heads1I. The plate brushes 5| have short conducting wires or jumpers 15secured thereto in a conventional manner, and at their free ends thejumpers 15 carry terminal washers 16 for engagement beneath the heads 14of the conducting rivets, Figure 13. Lead wires 11 and'18 from thestarting stator winding of the motor have their 'free ends insertedwithin the bores of the .tubular rivets 12, from the ends of the rivetsremote from their heads 14. The lead wires have their ends soldered inplace within the rivets, as shown at 19. The extensions or arms 55 and62 are sufciently resilient so that they may be sprung outwardly forremoving the pins 56 and 63 from the openings 51 of the plate brushes,as when changing the plate brushes, or the like. The bar 68 may besecured to some stationary part of the motor by a bolt, or the like, asshown, passed through one of the openings 69.

The operation of the switch is as follows:

The disc or carrier I5 is applied to the armature shaft S for rotationtherewith, the bore I9 receiving the armature shaft. The motor may be ofthe split phase type or of the capacitive type. The split phase motorhas a starting stator wind; ing, and a running stator winding. As iswell known, in starting a motor of this type, current is rst supplied tothe starting and running stator windings, and when vthe motor speedincreases to the desired point, the current to the starting statorwinding is cut off. The present switch is employedfto supply current tothe starting stator winding to start the motor, and to cut thecurrentoff. when the motor speeds up.. It is desirable to cut off .the currentto the starting stator winding when the motor reaches approximately .80rpercent of .motor speed. It is further desirable, when the motor isslowing down, to have the circuit through the starting stator windingclosed .at a motor speed somewhat lower than'80 percent of ,full speed,and our switch accomplishes these objectives.

When the motor .armature shaft .S` is at rest, the switch is closed,Figure 4. The toggle spring 35 swings the conducting segment 21 radiallyinwardly so that the contact 59 engages the contact 49, thus closing thecircuit between the slip rings 42 and. 43 and plate brushes 5I, in turnclosing a circuit through the starting stator winding. As the speed ofthe armature shaft increases, the disc I5 has its rotational speedcorrespondingly increased and the pivoted conducting segment 21 swingsradially outwardly within the slot 25 by centrifugal force in oppositionto the spring 35 when the selected speed is reached. When the conductingsegment 21 thus swings radially outwardly the engagement betweencontacting pins 49 and '58 is broken and the circuit is opened. Aspreviously stated, the conducting segment 21 should swing radiallyoutwardly to break the circuit at the contact points 49 and 5U when themotor has reached approximately percent of full speed, although thisgure may vary slightly with different motors. The toggle spring 35 isaccordingly designed to permit the segment 21 to open at the properspeed for the particular motor. The toggle spring 35 is designed andmounted so that vthe segment 21 will be moved inwardly radially by thetoggle spring for again closing the circuit through the starting statorwinding when the motor is slowing down and has reached a speed somewhatlower than 80l percent of full speed. In order that the vsegment 21 mayswing inwardly at a lower rotational speed than was required to shift itoutwardly, the toggle switch 35 exerts a lesser force radially inwardlywhen the segment 21 is in the outer position, Figure 5, than it exertswhen the segment 21 is in the innermost position. With the conductingsegment 21 in the inner position, Figure 4, the free end of the innerside 35' of the toggle spring is positioned radially inwardly of thecentral longitudinal axis of the pin 32 and this toggle switch exerts arelatively large component of force in the radial inward direction toswing the segment 21 inwardly. When the segment 21 swings outwardly at80 percent of full motor speed, to the position shown in Figure 5, theside 35' of the toggle spring asr its free end swung outwardly and Vsuchfree end is now in substantial alignment with the central longitudinalaxis of pin 32. The component force in the radially inward Vdirectionexerted by the side 35 is relatively less than it previously exerted inthe position of Figure 4, and consequently the spring 35 will not causelthe segment 21 to again swing to the inner position of Figure 4, untilthe speed of the motor has decreased to a point somewhat below 80percent of full speed, which is desirable. This toggle action producedby the spring 35 for causing the circuit through the starting statorwinding to open and close at different speeds cannot 7 be produced by aspring which exerts a constant radial component of force.

To further illustrate the differential 'forces produced by the spring35, for different positions of the side 35', see the vector diagrams,Figures 4 and 5. In Figure 4, the diagonal vectorillustrates theresultant force produced by the spring when the conducting segment 21 isclosed. The vertical or radial component of this resultant force isrelatively large. In Figure 5, the diagonal vector again represents theresultant force produced by the spring and here the vertical or radialcomponent is relatively small, with the segment in its outermostposition.

Our centrifugal switch is highly compact and narrow. The parts aresubject to substantially no wear, except where the plate brushes 5|engage the brush plates 42 and 43, and here, wear is slight, since thecontact area between the plate brushes and slip rings is large. It ispractically impossible for dirt to enter the slot 2i), as previouslystated. Due to the construction including the plates 54 and 6| andassociated elements, it is highly improbable that a short circuit everwill occur.

The switch is very easily assembled and disassembled. rlhe plate brushes5| may be disengaged from between the annular flanges l5 and d4 byspringing the arms 55 and 62 outwardly. The brush plates 42 and li3 arereadily removable and may be lifted from contact with the opposite sidesof the disc l5. When the insulating washer 46 has been removed, thecontact segment and spring 35 may be pushed laterally from the slot 2D.

In Figures 14 to 18, inclusive, I have shown a modified form of meansfor holding the plate brushes in place. This means comprises anupstanding metal rod 89 to be connected at its lower end with astationary part of the motor. The upper portion of this rod is screwthreaded as shown'at 8|. Mounted upon the screw threaded portion 8| ofthe rod is an insulating sleeve 82, and insulatingwwashers 83 and Bilare mounted upon the screw threaded portion 8| above and below thesleeve 8|. The screw threaded portion 8| carries a lower nut `85 and anupper nut 86 and a lock. nut 8l. The washers 33 have notches 86 formedtherein. The sleeve 82 has a fiat 31. The sleeve s2 carries aninsulating washer 88.

Tortional coil springs 89 and @il are mounted upon the sleeve 82 betweenthe insulating washers 83 and BS and are insulated from each other.Corresponding outer ends of the coil springs are bent to provide radialextensions el, Figure 18, held within a longitudinal groove 92, formedin the sleeve `32. The inner ends of the springs 89 and Bil arecontinued in the form of resilient arms 93, having extensions ed,provided with ends 95, bent at a right angle thereto. These ends 95 areinserted within the openings 51 of the plate brushes 5|. The springsserve to hold the plate brushes in place and yieldingly press the sameinto engagement with the faces of the slip rings 42 and 43. The springsare in electrical connection with the slip rings. c,

Metal strips or tabs 96 are inserted within the outer ends of springs 89and 9|] and engage the flat 43l and are in electrical contact with thesesprings and have lateral extensions 91, held within the notches 86. Theouter ends of these lateral extensions are bent into loops 98, as shown.Insulated wires 99, corresponding to wires 'l5 are permanentlyelectrically connected with the plate brushes 5l and the outer ends orthese wires 99 are inserted within the loops 98. The ends of lead wires|00 arey also inserted in these loops and the loops are pinched upon thewires to form a rm electrical engagement. All other parts of the switchremain identical with those shown described in connection with the firstform of the invention.

In view of the description of the portion of the first form of theinvention it is thought that it is unnecessary to describe any furtheroperation.

It is to be understood that the forms of our invention herewith shownand described are to be taken as preferred examples of the same, andthat various changes in the shape, size, and arrangement of parts, maybe resorted to without departing from the spirit of our invention or thescope of the subjoined claims.

Having thus described our invention, we claim:

l. A centrifugal force actuated switch, comprising an insulating disc tobe mounted upon the armature shaft of a motor, said disc having opposedsubstantially radial faces, said disc having a recess formed thereinwhich extends through the opposed faces, brush plates arrangedsubstantially radially on edge and disposed adjacent to the opposedfaces of the disc and secured to the disc, the brush plates havingsubstantially annular guide flanges projecting axially beyond the outerfaces of the brush plates, centrifugally operated means arranged withinthe recess to electrically connect and disconnect the brush plates, theends of the recess being covered by the brush plates, plate brushesarranges substantially radially on edge and having side faces contactingwith the outer faces of the brush plates and engaging the substantiallyannular flanges to be guided thereby, and resiliant means engaging theplate brushes to force them against the opposed faces of the brushplates and to hold them against rotation with the brush plates.

2. A centrifugal force actuated switch, comprising an insulating disc tobe mounted upon the armature shaft of a motor, said disc having opposedsubstantially radial faces, brush plates arranged substantially radiallyon edge and disposed adjacent to the opposed faces of the disc andsecured to the disc, each brush plate having substantially annular guideflanges projecting axially beyond the outer face of the brush plates,centrifugally operated means mounted upon the disc to electricallyconnect and disconnect the brush plates, plate brushes arrangedsubstantially radially on edge and having side faces contacting with theouter faces of the brush plates, the plate brushes being arrangedbetween the annular flanges to be held in place thereby, and resilientmeans engaging the plate brushes t0 force them against the opposed facesof the brush plates and to hold them against rotation with the brushplates.

3. A centrifugal force actuated switch, comprising an insulating disc tobe mounted upon the iarmature shaft of a motor, said disc having opposedsubstantially radially extending faces, brush plates arrangedsubstantially radially on edge and arranged adjacent to the opposedfaces and secured to the discs, each brush plate having spacedsubstantially-annular guide flanges projecting axially beyond the outerface of the brush plate, means including plate brushes arrangedsubstantially radially on edge and having inner faces engaging the outerfaces of the brush plates and arranged betweenv the flanges to be heldin place by the ilanges, and centrifugally operated means mounted uponthe disc to electrically connect and disconnect the brush plates.

4. A centrifugal force actuated switch, comprising a rotatablesupporting member, an elongated oentrifugally operated currentconducting member, means pivotally mounting one end of the currentconducting member upon the supporting member, the opposite end of thecurrent conducting member being free and moved radially outwardly bycentrifugal force, a relatively stationary contact mounted upon thesupporting member for electrical connection with the current conductingmember when such current conducting member is in the inner position,means for connecting the current conducting member with one side of acircuit, means for connecting the contact with the opposite side of thecircuit, and a spring consisting of a single substantially U-shapedportion including opposed overlapping inner and outer arms, the outerarm engaging the supporting member near the free end Of the outer arm sothat the U-shaped portion may rock bodily upon the supporting member andthe inner arm of the substantially U-shaped portion engaging the freeend of the current conducting member, the U-shaped portion having itsopen end arranged next to the free end of the current conducting memberand disposed in end-to-end relation with the current conducting member,the point of engagement between the free end of the inner arm and thecurrent conducting member being changed with respect to the pivot of thecurrent conducting member when the free end of such current conductingmember moves radially.

5. A centrifugal force actuated switch, comprising a rotatablesupporting member, a rigid centrifuga-ily operated current conductingmember extending circumferentially of the supporting member and havingone end pivotally mounted upon the supporting member, a relatively sta--tionary contact mounted upon the supporting member and arranged upon theinner side of the current conducting member for coaction therewith,means for connecting the current conducting member with one side of acircuit, means for connecting the contact with the opposite side of thecircuit, and a single substantially U-shaped differential spring havingopposed inner and outer overlapping arms, the substantially U- shapedspring being arranged in end-to-end relation with the current conductingmember and having its open end disposed next to the free end of thecurrent conducting member, the outer arm having its free end mountedupon the supporting member, the inner arm engaging the free end of thecurrent conducting member, the point of engagement between the inner armand the current conducting member being changed with respect to thepivot of the current conducting member when the free end of the currentconducting member moves radially.

WILLIS Z. WEST, JR. MORGAN F. GAMBLE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name

